There can be no doubt that denervation of skeletal muscle brings about profound alterations in the functional integrity of the sarcolemma. Although precise structure-function relationships of sarcolemmal macromolecular constituents have not been established, recent biochemical evidence indicates that muscle surface membranes are, indeed, physically altered from the normal state. Work in this laboratory demonstrated that shortly after denervation of rat skeletal muscle the activity of a number of degradative enzymes was greatly increased. Furthermore, the increased activity of at least two glycoside hydrolases was shown to be influenced by some factor in the nerve supplying the muscle or by some process which the nerve mediated. In the presently proposed research we intend to examine these phenomena in greater detail and to extend this type of approach to "synthetic enzyme systems" (i.e., enzymes responsible for synthesis of glycoconjugates) as well. It is hoped that the important parameters regulating muscle macromolecular metabolism which are altered by denervation can be determined, with the aim of eventually relating these perturbations to the regulation of particular macromolecular constituents of muscle surface membranes.